The present invention relates to the field of microwave thermal therapy of tissue. In particular, the present invention provides rectal cooling in conjunction with heating of diseased intraprostatic tissue.
The prostate gland is a complex, chestnut-shaped organ which encircles the urethra immediately below the bladder. This relatively small organ, which is the most frequently diseased of all internal organs, is the site of a common affliction among older men: benign prostatic hyperplasia (BPH), as well as a more serious affliction, cancer. BPH is a nonmalignant, bilateral nodular expansion of the prostate tissue occurring mainly in the transition zone of the prostate. Left untreated, BPH causes obstruction of the urethra which usually results in increased urinary frequency, urgency, incontinence, nocturia and slow or interrupted urinary stream. BPH may also result in more severe complication, such as urinary tract infection, acute urinary retention, hydronephrosis and uraemia.
Recently developed treatments of BPH include transurethral microwave thermal therapy in which microwave energy is employed to elevate the temperature of diseased intraprostatic tissue surrounding the urethra above about 45.degree. C. thereby thermally damaging the tumorous BPH tissue. Delivery of microwave energy to tumorous prostatic tissue is generally accomplished through use of a transurethral microwave antenna-containing applicator or catheter positioned within the urethra adjacent the prostate gland. The microwave antenna, when energized, heats adjacent tissue due to molecular excitation and generates a cylindrically symmetrical radiation pattern which encompasses and necroses the tumorous intraprostatic tissue. The necrosed intraprostatic tissue is subsequently reabsorbed by the body, thereby relieving an individual from the symptoms of BPH.
While transurethral microwave thermal therapy mininizes the distance between a microwave antenna-carrying applicator and the transition zone of the prostate gland, there is still concern that healthy tissue located within the radiation pattern of the microwave antenna may be thermally damaged. In particular, rectal wall and adjacent tissue may be thermally damaged during a therapy session depending upon the length of time of the therapy session and the strength of the microwave signal transmitted from the microwave antenna.
Therefore, there is a need for a system and a method which will protect rectal wall and adjacent tissue from thermal damage during a transurethral microwave thermal therapy session in which tumorous prostatic tissue is necrosed.